阅读说明：本技术 侧行链路单播通信调度 (Sidelink unicast communication scheduling ) 是由 吴志斌 K·古拉蒂 H·程 S·K·巴盖尔 厉隽怿 于 2020-04-30 设计创作，主要内容包括：提供了用于支持多个用户设备(UE)之间的侧行链路通信并且可以在各种装置、方法和/或制品中实现的技术。在某些方面中,第一UE可以与第二UE建立侧行链路调度,其中,侧行链路调度对应于由一个或多个对应的链路可用性调度等指示的可用于第一UE和第二UE两者的通信资源的至少子集。然后,两个UE可以根据侧行链路调度与第二UE建立侧行链路。在某些实例中,可以就多个侧行链路调度达成一致,使得UE可以根据需要动态地从一个调度切换到另一调度。(Techniques are provided for supporting sidelink communications between a plurality of User Equipments (UEs) and may be implemented in various apparatuses, methods, and/or articles of manufacture. In certain aspects, a first UE may establish a sidelink schedule with a second UE, where the sidelink schedule corresponds to at least a subset of communication resources available to both the first UE and the second UE as indicated by one or more corresponding link availability schedules, or the like. The two UEs may then establish a sidelink with the second UE according to the sidelink schedule. In some instances, multiple sidelink schedules may be agreed upon such that the UE may dynamically switch from one schedule to another as needed.)

1. A method for use in sidelink unicast communications, the method comprising: at a first User Equipment (UE), performing the following:

obtaining a link availability schedule that indicates, at least in part, communication resources available for use by at least the first UE for sidelink unicast communications;

identifying a second UE attempting to participate in the sidelink unicast communication;

establishing a sidelink schedule with the second UE, the sidelink schedule corresponding to at least a subset of the communication resources indicated by the link availability schedule;

establishing a sidelink with the second UE; and

communicate with the second UE via the sidelink according to the sidelink schedule using at least a portion of the communication resources.

2. The method of claim 1, wherein establishing the sidelink schedule comprises: exchanging sidelink negotiation information with the second UE, wherein at least a portion of the sidelink negotiation information provided by the first UE to the second UE is based, at least in part, on the link availability schedule.

3. The method of claim 2, wherein at least a portion of the sidelink negotiation information is indicative of at least one quality of service (QoS) parameter corresponding to the sidelink unicast communication.

4. The method of claim 2, wherein at least a portion of the sidelink negotiation information is exchanged as part of an RRC procedure or as part of a MAC procedure.

5. The method of claim 1, wherein the sidelink schedule comprises two or more candidate sidelink schedules acceptable to the first UE and the second UE.

6. The method of claim 1, wherein the sidelink schedule indicates the following:

a first resource for the first UE to use for transmitting signals on the sidelink to the second UE;

a second resource for the first UE to receive signals from the first UE on the sidelink; or

Both the first resource and the second resource.

7. The method of claim 1, wherein the link availability schedule is based at least in part on a network-defined communication resource allocation.

8. The method of claim 1, wherein the sidelink scheduling indicates a network-related timing offset for at least one communication resource used by the first UE for transmitting to the second UE via the sidelink.

9. The method of claim 1, wherein the sidelink comprises a PC5 communication link.

10. A first User Equipment (UE), comprising:

a transceiver;

a memory; and

one or more processing units coupled to the transceiver and memory, and wherein the one or more processing units are configured to:

accessing a link availability schedule stored in the memory, the link availability schedule indicating, at least in part, communication resources available for use by at least the first UE for sidelink unicast communications;

identifying a second UE attempting to participate in the sidelink unicast communication;

communicating with the second UE via the transceiver to establish a sidelink schedule corresponding to at least a subset of the communication resources indicated by the link availability schedule; and

communicate with the second UE via the transceiver on a sidelink using at least a portion of the communication resources in accordance with the sidelink schedule.

11. The first UE of claim 10, and wherein the one or more processors are further configured to: exchanging, at least in part via the transceiver, sidelink negotiation information with the second UE, wherein at least a portion of the sidelink negotiation information provided by the first UE to the second UE is based, at least in part, on the link availability schedule.

12. The first UE of claim 11, wherein at least a portion of the sidelink negotiation information is indicative of at least one quality of service (QoS) parameter corresponding to the sidelink unicast communication.

13. The first UE of claim 11,

wherein at least a portion of the sidelink negotiation information is exchanged as part of an RRC procedure or as part of a MAC procedure.

14. The first UE of claim 10, wherein the sidelink schedule comprises two or more candidate sidelink schedules acceptable to the first UE and the second UE.

15. The first UE of claim 14 and wherein said one or more processors are further configured to: identifying that one of the two or more candidate sidelink schedules is to be used as the sidelink schedule at least for transmitting signals to the second UE via the sidelink.

16. The first UE of claim 10, wherein the sidelink scheduling indicates:

a first resource for the first UE to use for transmitting signals on the sidelink to the second UE;

a second resource for the first UE to receive signals from the first UE on the sidelink; or

Both the first resource and the second resource.

17. The first UE of claim 10, wherein at least a portion of the communication resources available for use by the first UE for sidelink unicast communications are also available for use by the second UE for possible sidelink unicast communications.

18. The first UE of claim 10, wherein the link availability schedule is based at least in part on a network-defined communication resource allocation.

19. The first UE of claim 10, wherein the sidelink comprises: a single unidirectional sidelink; two unidirectional sidelink arranged in reverse to provide bidirectional communication; a bidirectional sidelink; or some combination thereof.

20. The first UE of claim 10, wherein the sidelink schedule indicates a communication resource granularity.

21. An apparatus for sidelink unicast communication at a first User Equipment (UE), the apparatus comprising:

means for obtaining a link availability schedule that indicates, at least in part, communication resources available for use by at least the first UE for sidelink unicast communications;

means for identifying a second UE attempting to participate in a sidelink unicast communication;

means for establishing a sidelink schedule with the second UE, the sidelink schedule corresponding to at least a subset of the communication resources indicated by the link availability schedule;

means for establishing a sidelink with the second UE; and

means for communicating with the second UE via the sidelink using at least a portion of the communication resources in accordance with the sidelink schedule.

22. The apparatus of claim 21, wherein the means for establishing the sidelink schedule comprises:

means for exchanging sidelink negotiation information with the second UE, wherein at least a portion of the sidelink negotiation information provided by the first UE to the second UE is based, at least in part, on the link availability schedule.

23. The apparatus of claim 22, wherein at least a portion of the sidelink negotiation information indicates at least one quality of service (QoS) parameter corresponding to the sidelink unicast communication and exchanged as part of an RRC procedure or as part of a MAC procedure.

24. The apparatus of claim 1, wherein the sidelink schedule comprises two or more candidate sidelink schedules acceptable to the first UE and the second UE, and indicates:

a first resource for the first UE to use for transmitting signals on the sidelink to the second UE;

a second resource for the first UE to receive signals from the first UE on the sidelink; or

Both the first resource and the second resource.

25. The apparatus of claim 21, wherein the link availability schedule is based at least in part on a network-defined communication resource allocation.

26. An article of manufacture, comprising:

a non-transitory computer-readable medium having instructions stored therein, the instructions being executable by one or more processing units of a first User Equipment (UE) to:

accessing a link availability schedule that indicates, at least in part, communication resources available for use by at least the first UE for sidelink unicast communications;

identifying a second UE attempting to participate in the sidelink unicast communication;

initiating communication with the second UE to establish a sidelink schedule corresponding to at least a subset of the communication resources indicated by the link availability schedule; and

initiating communication with the second UE on a sidelink using at least a portion of the communication resources in accordance with the sidelink schedule.

27. The article of claim 26, wherein said instructions are further executable by one or more processing units to:

exchanging sidelink negotiation information with the second UE, wherein at least a portion of the sidelink negotiation information provided by the first UE to the second UE is based, at least in part, on the link availability schedule.

28. The article of manufacture of claim 27, wherein at least a portion of the sidelink negotiation information is indicative of at least one quality of service (QoS) parameter corresponding to the sidelink unicast communication, and the sidelink scheduling comprises two or more candidate sidelink schedules acceptable to the first UE and the second UE.

29. The article of manufacture of claim 26, wherein at least a portion of the communication resources available for use by the first UE for sidelink unicast communications are also available for use by the second UE for possible sidelink unicast communications.

30. The article of manufacture of claim 26, wherein the link availability schedule is based at least in part on a network-defined communication resource allocation.

Technical Field

The following relates generally to wireless communications and, more particularly, to sidelink communications.

Background

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems are capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems, such as Long Term Evolution (LTE) systems, LTE-advanced (LTE-a) systems, or LTE-a professional systems, and fifth generation (5G) systems, which may be referred to as New Radio (NR) systems. These systems may employ techniques such as: code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple-access communication system may include multiple base stations or network access nodes, each supporting communication for multiple communication devices (which may otherwise be referred to as User Equipment (UE)) simultaneously.

In some wireless communication systems, communication may occur directly between UEs, e.g., in a device-to-device (D2D) or peer-to-peer (P2P) fashion, typically using communication resources shared by one or more networks that may serve such or other similar UEs. For example, some such communications in the 5G NR may be referred to as unicast sidelink communications. In some implementations, sidelink communications may be conducted by two UEs using communication resources, which may be allocated by the network for use by a single UE or allocated to multiple UEs in some shared manner. The unicast sidelink may be limited to half-duplex communication between a pair of UEs, if: wherein at least one of the UEs is unable to simultaneously transmit and receive signals. Further, there may be the following cases: among other things, the transmitting UE may need to retransmit data messages that may have been missed by the receiving UE, which may have been transmitting a signal by itself and thus not receiving, or may have been tuned to receive other signals via resources (e.g., time and frequency based slots, etc.) that may not include a signal from the transmitting UE. Likewise, if other devices can use the shared resources for other communications, there may be signal interference that also results in retransmissions by the transmitting UE. Accordingly, improved techniques may be beneficial by improving efficient utilization of resources (e.g., by reducing retransmissions).

Disclosure of Invention

According to certain aspects, a method is provided for establishing a sidelink unicast communication, e.g., between a first User Equipment (UE) and a second UE. For example, a first UE may be configured to perform a method comprising: obtaining a link availability schedule that indicates, at least in part, communication resources available for use by at least a first UE for sidelink unicast communications; identifying a second UE attempting to participate in the sidelink unicast communication; establishing a sidelink schedule with the second UE, the sidelink schedule corresponding to at least a subset of the communication resources indicated by the link availability schedule; establishing a sidelink with a second UE; and communicating with the second UE via the sidelink using at least a portion of the communication resources in accordance with the sidelink schedule.

According to certain other aspects, a (first) UE may be provided that includes at least one transceiver, a memory, and one or more processing units coupled to the transceiver and the memory, and wherein the one or more processing units are configured to: accessing a link availability schedule stored in a memory, the link availability schedule indicating, at least in part, communication resources available for use by at least a first UE for sidelink unicast communications; identifying a second UE attempting to participate in the sidelink unicast communication; communicating with a second UE via a transceiver to establish a sidelink schedule corresponding to at least a subset of the communication resources indicated by the link availability schedule; and communicating with the second UE via the transceiver on the sidelink using at least a portion of the communication resources according to the sidelink schedule.

According to other aspects, an apparatus is provided for sidelink unicast communication at a (first) UE. The apparatus may include: means for obtaining a link availability schedule that indicates, at least in part, communication resources available for use by at least a first UE for sidelink unicast communication; means for identifying a second UE attempting to participate in a sidelink unicast communication; means for establishing a sidelink schedule with a second UE, the sidelink schedule corresponding to at least a subset of the communication resources indicated by the link availability schedule; means for establishing a sidelink with a second UE; and means for communicating with the second UE via the sidelink using at least a portion of the communication resources in accordance with the sidelink schedule.

According to other aspects, an article is provided, comprising: a non-transitory computer-readable medium having instructions stored therein, the instructions being executable by one or more processing units of a (first) UE to: accessing a link availability schedule that indicates, at least in part, communication resources available for use by at least a first UE for sidelink unicast communications; identifying a second UE attempting to participate in the sidelink unicast communication; initiating communication with a second UE to establish a sidelink schedule corresponding to at least a subset of the communication resources indicated by the link availability schedule; and initiating communication with the second UE on the sidelink using at least a portion of the communication resources in accordance with the sidelink schedule.

Drawings

Fig. 1 illustrates an example of a system for wireless communication with a User Equipment (UE) configured for sidelink unicast communication, or the like, in accordance with certain aspects of the present disclosure.

Fig. 2 is a block diagram illustrating some features of an apparatus for use in a UE configured for sidelink unicast communication based, at least in part, on one or more sidelink schedules negotiated with a peer UE, in accordance with certain aspects of the present disclosure.

Fig. 3 is a timeline illustrating some example signaling between two UEs that may be used to establish a sidelink unicast communication therebetween, in accordance with certain aspects of the present disclosure.

Fig. 4 illustrates portions of an example resource map that may indicate, at least in part, information for link availability scheduling or other similar communication resource allocation for a UE in accordance with certain aspects of the present disclosure.

Fig. 5 illustrates some example link availability schedules for a UE in accordance with certain aspects of the present disclosure.

Fig. 6, 7, and 8 illustrate some resources indicated as part of some example scheduling processes, in accordance with certain aspects of the present disclosure.

Fig. 9 is a flow diagram illustrating an example method for use in a UE configured for sidelink unicast communication based at least in part on one or more sidelink schedules, e.g., as shown in fig. 2, in accordance with certain aspects of the present disclosure.

Detailed Description

As described in more detail in the specification and examples herein, techniques are provided that may improve the efficiency of sidelink unicast communications, for example, by allowing a UE to establish and/or otherwise utilize sidelink scheduling. In some instances, retransmission may be reduced using sidelink scheduling.

As an initial example, the first UE may include a sidelink scheduler configured to access or otherwise obtain a link availability schedule that indicates, at least in part, communication resources that may be available for use by at least the first UE for sidelink unicast communications. In certain example implementations, all or a portion of the link availability schedule may be obtained from network resources and indicate, at least in part, communication resources that may be allocated or otherwise allocated for sharing by the first UE. When the first UE has identified a second UE attempting to participate in sidelink unicast communications, the sidelink scheduler may establish one or more sidelink schedules with the second UE. Here, for example, the sidelink schedule may correspond to at least a subset of the communication resources indicated by the link availability schedule. The UE may then establish a sidelink with a second UE based on the sidelink schedule and use the sidelink.

In some examples, establishing the sidelink schedule includes: one or both of the UEs may exchange sidelink negotiation information, some of which may be scheduled based at least in part on link availability. For example, as part of exchanging sidelink negotiation information with the second UE, the first UE may receive sidelink negotiation information from the second UE, which may correspond to a link availability schedule applicable to the second UE. In some example implementations, at least a portion of the sidelink negotiation information may indicate at least one quality of service (QoS) parameter, etc., corresponding to sidelink unicast communications. As given by way of example herein, at least a portion of the sidelink negotiation information that may be exchanged as part of an RRC procedure, a MAC procedure, and/or other similar protocol layers, or some combination thereof.

In some example implementations, the sidelink schedules that may be negotiated or otherwise established may include two or more candidate sidelink schedules that are acceptable to the first UE and the second UE. Thus, for example, one or both of the UEs may be configured to identify that a particular candidate sidelink schedule is to be used (e.g., as a sidelink schedule). For example, the first UE may send or receive an indication that a particular candidate sidelink schedule is to be used as a sidelink schedule.

While the sidelink schedule may indicate particular resources available to the first UE for transmitting signals to the second UE on the sidelink, the first UE may actually be configured to transmit one or more signals to a device other than the second UE using the particular resources, or may receive one or more signals from another device, or may be some combination thereof. Similar capabilities may exist for the second UE to perform other communications that may not actually involve the first UE. Similarly, the sidelink schedule may indicate particular resources for the first UE to use to receive signals from the first UE on the sidelink (and vice versa).

As mentioned, the sidelink schedule may correspond to at least a subset of the communication resources indicated by the link availability schedule. For example, the subset of communication resources may correspond to at least one subframe of at least one time slot indicated by the link availability schedule. Here, the slot may indicate the resource by time and frequency, for example. The sidelink schedule may indicate a communication resource granularity (time, frequency, or both). The sidelink schedule may indicate a network-related timing offset for at least one communication resource for sidelink unicast communications, and/or the like.

In some instances, the sidelink may comprise a single unidirectional sidelink, at least two unidirectional sidelinks arranged in reverse to provide bidirectional communication, a bidirectional sidelink, or some combination thereof. In some instances, the sidelink may include a PC5 or other similar communication link.

Attention is now directed to fig. 1, which illustrates an example of a wireless communication system 100 that supports sidelink establishment in accordance with aspects of the present disclosure. The wireless communication system 100 includes base stations 105, UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an LTE-advanced (LTE-a) network, an LTE-a professional network, or a New Radio (NR) network. In some cases, the wireless communication system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low cost and low complexity devices.

The base station 105 may communicate wirelessly with the UE 115 via one or more base station antennas. The base stations 105 described herein may include or may be referred to by those skilled in the art as base station transceivers, wireless base stations, access points, radio transceivers, node bs, evolved node bs (enbs), next generation node bs or gigabit node bs (any of which may be referred to as gnbs), home node bs, home evolved node bs, or some other suitable terminology. The wireless communication system 100 may include different types of base stations 105 (e.g., macro cell base stations or small cell base stations). The UE 115 described herein is capable of communicating with various types of base stations 105 and network devices, including macro enbs, small cell enbs, gnbs, relay base stations, and the like.

Each base station 105 may be associated with a particular geographic coverage area 110 in which communications with various UEs 115 are supported. Each base station 105 may provide communication coverage for a respective geographic coverage area 110 via a communication link 125, and the communication link 125 between the base station 105 and the UE 115 may utilize one or more carriers. The communication links 125 shown in the wireless communication system 100 may include: uplink transmissions from the UE 115 to the base station 105, or downlink transmissions from the base station 105 to the UE 115. Downlink transmissions may also be referred to as forward link transmissions, and uplink transmissions may also be referred to as reverse link transmissions.

The geographic coverage area 110 for a base station 105 can be divided into sectors that form a portion of the geographic coverage area 110, and each sector can be associated with a cell. For example, each base station 105 may provide communication coverage for a macro cell, a small cell, a hot spot, or other type of cell, or various combinations thereof. In some examples, the base stations 105 may be mobile and, thus, provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, and the overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station 105 or different base stations 105. The wireless communication system 100 may include, for example, heterogeneous LTE/LTE-a professional or NR networks, where different types of base stations 105 provide coverage for various geographic coverage areas 110.

The term "cell" refers to a logical communication entity used for communication with the base station 105 (e.g., on a carrier) and may be associated with an identifier (e.g., Physical Cell Identifier (PCID), Virtual Cell Identifier (VCID)) used to distinguish neighboring cells operating via the same or different carrier. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., Machine Type Communication (MTC), narrowband internet of things (NB-IoT), enhanced mobile broadband (eMBB), or other protocol types) that may provide access for different types of devices. In some cases, the term "cell" may refer to a portion (e.g., a sector) of geographic coverage area 110 over which a logical entity operates.

UEs 115 may be dispersed throughout the wireless communication system 100, and each UE 115 may be stationary or mobile. The UE 115 may also be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a user equipment, or some other suitable terminology, where a "device" may also be referred to as a unit, station, terminal, or client. The UE 115 may be a personal electronic device, such as a cellular telephone, a Personal Digital Assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, the UE 115 may also refer to a Wireless Local Loop (WLL) station, an internet of things (IoT) device, an internet of everything (IoE) device, or an MTC device, etc., which may be implemented in various items such as appliances, vehicles, meters, etc.

Some UEs 115 (e.g., MTC or IoT devices) may be low cost or low complexity devices and may provide automated communication between machines (e.g., communication via machine-to-machine (M2M)). M2M communication or MTC may refer to data communication techniques that allow devices to communicate with each other or with a base station 105 without human intervention. In some examples, M2M communication or MTC may include communication from devices that integrate sensors or meters to measure or capture information and relay that information to a central server or application that may utilize the information or present the information to a human interacting with the program or application. Some UEs 115 may be designed to collect information or implement automated behavior of machines. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, device monitoring, healthcare monitoring, wildlife monitoring, climate and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based billing for services.

Some UEs 115 may be configured to employ a reduced power consumption mode of operation, such as half-duplex communications (e.g., a mode that supports unidirectional communication via transmission or reception rather than simultaneous transmission and reception). In some examples, half-duplex communication may be performed at a reduced peak rate. Other power saving techniques for the UE 115 include: enter a power-saving "deep sleep" mode when not engaged in active communications, or operate on a limited bandwidth (e.g., in accordance with narrowband communications). In some cases, the UE 115 may be designed to support critical functions (e.g., mission critical functions), and the wireless communication system 100 may be configured to provide ultra-reliable communication for these functions.

The wireless communication system 100 may support direct communication (e.g., using peer-to-peer (P2P), device-to-device (D2D) protocols, ProSe direct communication) between UEs 115 on the sidelink 135. Sidelink communications may be used for D2D media sharing, vehicle-to-vehicle (V2V) communications, V2X communications (e.g., cellular V2X (cV2X) communications, enhanced V2X (eV2X) communications, etc.), emergency rescue applications, and so forth. One or more UEs 115 in the group of UEs 115 communicating with D2D may be within the geographic coverage area 110 of the base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of the base station 105 or otherwise unable to receive transmissions from the base station 105. In some cases, multiple groups of UEs 115 communicating via D2D communication may utilize a one-to-many (1: M) system, where each UE 115 transmits to every other UE 115 in the group. In some cases, the base station 105 facilitates scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving base stations 105, e.g., particularly using the techniques for sidelink scheduling presented herein.

The base stations 105 may communicate with the core network 130 and with each other. For example, the base stations 105 may interface with the core network 130 over backhaul links 132 (e.g., via S1, N2, N3, or other interfaces). The base stations 105 may communicate with each other directly (e.g., directly between base stations 105) or indirectly (e.g., via the core network 130) over backhaul links 134 (e.g., via X2, Xn, or other interfaces).

Core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. Core network 130 may be an Evolved Packet Core (EPC) that may include at least one Mobility Management Entity (MME), at least one serving gateway (S-GW), and at least one Packet Data Network (PDN) gateway (P-GW). The MME may manage non-access stratum (e.g., control plane) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the EPC. User IP packets may be transported through the S-GW, which may itself be connected to the P-GW. The P-GW may provide IP address assignment as well as other functions. The P-GW may be connected to a network operator IP service. The operator IP services may include access to the internet, intranets, IP Multimedia Subsystem (IMS) or Packet Switched (PS) streaming services.

At least some of the network devices (e.g., base stations 105) may include subcomponents such as access network entities, which may be examples of Access Node Controllers (ANCs). Each access network entity may communicate with the UE 115 through a plurality of other access network transport entities, which may be referred to as radio heads, intelligent radio heads, or transmission/reception points (TRPs). In some configurations, the various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., base station 105).

Wireless communication system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Typically, the region from 300MHz to 3GHz is referred to as the Ultra High Frequency (UHF) region or decimeter band because the wavelength range is from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by building and environmental features. However, the waves may be sufficient to penetrate the structure for the macro cell to provide service to the UE 115 located indoors. UHF-wave transmission can be associated with smaller antennas and shorter distances (e.g., less than 100km) than transmission of smaller and longer waves using the High Frequency (HF) or Very High Frequency (VHF) portions of the spectrum below 300 MHz.

The wireless communication system 100 may also operate in the ultra high frequency (SHF) region using a frequency band from 3GHz to 30GHz, also referred to as a centimeter frequency band. The SHF area includes frequency bands such as the 5GHz industrial, scientific, and medical (ISM) band, which may be opportunistically used by devices that can tolerate interference from other users.

The wireless communication system 100 may also operate in the Extremely High Frequency (EHF) region of the spectrum, e.g., from 30GHz to 300GHz (also referred to as the millimeter-band). In some examples, the wireless communication system 100 may support millimeter wave (mmW) communication between the UE 115 and the base station 105, and EHF antennas of respective devices may be even smaller and more closely spaced compared to UHF antennas. In some cases, this may facilitate the use of antenna arrays within the UE 115. However, the propagation of EHF transmissions may suffer from even greater atmospheric attenuation and shorter distances than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions using one or more different frequency regions, and the specified use of frequency bands across these frequency regions may differ depending on the country or regulatory agency.

In some cases, the wireless communication system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may employ Licensed Assisted Access (LAA), LTE-unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band (e.g., the 5GHz ISM band). When operating in the unlicensed radio frequency spectrum band, wireless devices (e.g., base station 105 and UE 115) may employ a Listen Before Talk (LBT) procedure to ensure that a frequency channel is idle before transmitting data. In some cases, operation in the unlicensed band may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA). Operation in the unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer transmissions, or a combination of these. Duplexing in the unlicensed spectrum may be based on Frequency Division Duplexing (FDD), Time Division Duplexing (TDD), or a combination of the two.

In some examples, a base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. For example, the wireless communication system 100 may use a transmission scheme between a transmitting device (e.g., a first UE 115 of a sidelink connection) and a receiving device (e.g., a second UE 115 of the sidelink connection), where the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communication may employ multipath signal propagation to improve spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. For example, the multiple signals may be transmitted by the transmitting device via different antennas or different combinations of antennas. Also, the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO), in which multiple spatial layers are transmitted to the same receiving device, and multi-user MIMO (MU-MIMO), in which multiple spatial layers are transmitted to multiple devices.

Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting or receiving device (e.g., base station 105 or UE 115) to shape or steer an antenna beam (e.g., a transmit beam or a receive beam) along a spatial path between the transmitting and receiving devices. Beamforming may be achieved by: signals transmitted via the antenna elements of the antenna array are combined such that signals propagating in a particular orientation relative to the antenna array experience constructive interference while other signals experience destructive interference. The adjustment of the signal transmitted via the antenna element may comprise: a transmitting device or a receiving device applies certain amplitude and phase offsets to signals carried via each of the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to an antenna array of a transmitting device or a receiving device, or relative to some other orientation).

In one example, the base station 105 or the UE 115 may use multiple antennas or antenna arrays for beamforming operations for directional communications with the UE 115 receiver. For example, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times in different directions by the base station 105, which may include signals transmitted according to different sets of beamforming weights associated with different transmission directions. Transmissions in different beam directions may be used to identify beam directions (e.g., by the base station 105, the first UE 115, or a receiving device (e.g., the second UE 115)) for subsequent transmission and/or reception by the base station 105.

Some signals (e.g., data signals associated with a particular receiving device) may be transmitted by the base station 105 or the first UE 115 in a single beam direction (e.g., a direction associated with the receiving device (e.g., the second UE 115)). In some examples, a beam direction associated with a transmission along a single beam direction may be determined based at least in part on signals transmitted in different beam directions. For example, the receiving UE 115 may receive one or more of the signals transmitted in different directions by the base station 105 or the transmitting UE 115, and the receiving UE 115 may report an indication to the base station 105 or the transmitting UE 115 of the signal it receives with the highest signal quality or otherwise acceptable signal quality. Although the techniques are described with reference to signals transmitted by the base station 105 in one or more directions, the UE 115 may employ similar techniques to transmit signals multiple times in different directions (e.g., to identify beam directions for subsequent transmission or reception by the UE 115) or to transmit signals in a single direction (e.g., to transmit data to a receiving device).

When receiving various signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) from the base station 105, a receiving device (e.g., UE 115, which may be an example of a mmW receiving device) may attempt multiple receive beams. For example, the receiving device may attempt multiple receive directions by receiving via different antenna sub-arrays, by processing received signals according to different antenna sub-arrays, by receiving according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of an antenna array, or by processing received signals according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of an antenna array (any of the above operations may be referred to as "listening" according to different receive beams or receive directions). In some examples, a receiving device may use a single receive beam to receive along a single beam direction (e.g., when receiving data signals). The single receive beam may be aligned in a beam direction determined based at least in part on listening from different receive beam directions (e.g., a beam direction determined to have the highest signal strength, the highest signal-to-noise ratio, or otherwise acceptable signal quality based at least in part on listening from multiple beam directions).

In some cases, the antennas of a base station 105 or UE 115 may be located within one or more antenna arrays that may support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some cases, the antennas or antenna arrays associated with the base station 105 may be located at different geographic locations. The base station 105 may have an antenna array with multiple rows and columns of antenna ports that the base station 105 may use to support beamforming for communications with the UEs 115. Likewise, the UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.

In some cases, the wireless communication system 100 may be a packet-based network operating according to a layered protocol stack. In the user plane, communications at the bearer or PDCP layer may be IP-based. In the case of communication using D2D or V2X, the V2X layer may provide relevant protocols and, in some cases, may use ProSe direct communication protocols (e.g., PC5 signaling). The RLC layer may perform packet segmentation and reassembly to communicate on logical channels. The MAC layer may perform priority processing and multiplexing of logical channels to transport channels. The MAC layer may also use hybrid automatic repeat request (HARQ) to provide retransmissions at the MAC layer to improve link efficiency. In the control plane, the RRC protocol layer may provide for establishment, configuration, and maintenance of an RRC connection (which supports radio bearers for user plane data) between the UE 115 and the base station 105 or core network 130. At the PHY layer, transport channels may be mapped to physical channels.

In some cases, the UE 115 and the base station 105 may support retransmission of data to increase the likelihood that the data is successfully received. HARQ feedback is a technique that increases the likelihood that data will be received correctly on the communication link 125. HARQ may include a combination of error detection (e.g., using Cyclic Redundancy Check (CRC)), Forward Error Correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ may improve throughput at the MAC layer under poor radio conditions (e.g., signal and noise conditions). In some cases, a wireless device may support HARQ feedback for the same slot, where the device may provide HARQ feedback for data received in a previous symbol in a particular slot. In other cases, the device may provide HARQ feedback in subsequent time slots or according to some other time interval.

In LTE or NRMay be in basic time units (which may for example refer to T)_sA sampling period of 1/30,720,000 seconds). The time intervals of the communication resources may be organized according to radio frames each having a duration of 10 milliseconds (ms), where the frame period may be denoted as T_f＝307,200T_s. The radio frames may be identified by a System Frame Number (SFN) ranging from 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9, and each subframe may have a duration of 1 ms. A subframe may also be divided into 2 slots, each having a duration of 0.5ms, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix added in front of each symbol period). Each symbol period may contain 2048 sample periods, excluding the cyclic prefix. In some cases, a subframe may be the smallest scheduling unit of the wireless communication system 100 and may be referred to as a Transmission Time Interval (TTI). In other cases, the minimum scheduling unit of the wireless communication system 100 may be shorter than a subframe or may be dynamically selected (e.g., in bursts of shortened ttis (sTTI) or in selected component carriers using sTTI).

In some wireless communication systems, a slot may be further divided into a plurality of minislots comprising one or more symbols. In some examples, the symbol of the micro-slot or the micro-slot may be a minimum scheduling unit. Each symbol may vary in duration depending on, for example, the subcarrier spacing or frequency band of operation. Further, some wireless communication systems may implement timeslot aggregation, where multiple timeslots or minislots are aggregated together and used for communication between the UE 115 and the base station 105.

The term "carrier" refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communication over the communication link 125. For example, the carrier of the communication link 125 may include a portion of the radio frequency spectrum band that operates according to physical layer channels for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. The carriers may be associated with predefined frequency channels (e.g., evolved universal mobile telecommunications system terrestrial radio access (E-UTRA) absolute radio frequency channel numbers (EARFCNs)) and may be placed according to a channel grid for discovery by UEs 115. The carriers may be downlink or uplink (e.g., in FDD mode), or may be configured to carry downlink and uplink communications (e.g., in TDD mode). In some examples, the signal waveform transmitted on a carrier may be composed of multiple subcarriers (e.g., using multicarrier modulation (MCM) techniques such as Orthogonal Frequency Division Multiplexing (OFDM) or discrete fourier transform spread OFDM (DFT-S-OFDM)).

The organization of carriers may be different for different radio access technologies (e.g., LTE-A, LTE-a specialty, NR). For example, communications over carriers may be organized according to TTIs or slots, each of which may include user data as well as control information or signaling to support decoding of the user data. The carriers may also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc.) and control signaling that coordinates operation with respect to the carriers. In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers.

The physical channels may be multiplexed on the carriers according to various techniques. For example, physical control channels and physical data channels may be multiplexed on a downlink carrier using Time Division Multiplexing (TDM) techniques, Frequency Division Multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. In some examples, the control information sent in the physical control channel may be distributed in a cascaded manner between different control regions (e.g., between a common control region or common search space and one or more UE-specific control regions or UE-specific search spaces).

The carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples, the carrier bandwidth may be referred to as the carrier or "system bandwidth" of the wireless communication system 100. For example, the carrier bandwidth may be one of a plurality of predetermined bandwidths (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80MHz) of the carrier for the particular wireless access technology. In some examples, each served UE 115 may be configured to operate over part or all of the carrier bandwidth. In other examples, some UEs 115 may be configured for operation using a narrowband protocol type associated with a predefined portion or range within a carrier (e.g., a set of subcarriers or RBs) (e.g., "in-band" deployment of narrowband protocol types).

In a system employing MCM technology, a resource element may include one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme). Thus, the more resource elements the UE 115 receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE 115. In a MIMO system, wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers), and the use of multiple spatial layers may further increase the data rate for communication with the UE 115.

Devices of the wireless communication system 100 (e.g., base stations 105 or UEs 115) may have a hardware configuration that supports communication over a particular carrier bandwidth or may be configurable to support communication over one of a set of carrier bandwidths. In some examples, the wireless communication system 100 may include a base station 105 and/or a UE 115 that supports simultaneous communication via carriers associated with more than one different carrier bandwidth.

The wireless communication system 100 may support communication with UEs 115 over multiple cells or carriers, a feature that may be referred to as carrier aggregation or multi-carrier operation. According to a carrier aggregation configuration, a UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers. The carrier-aggregatable may be used with both FDD and TDD component carriers.

In some cases, the wireless communication system 100 may utilize an enhanced component carrier (eCC). An eCC may be characterized by one or more features including: a wider carrier or frequency channel bandwidth, a shorter symbol duration, a shorter TTI duration, or a modified control channel configuration. In some cases, an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have suboptimal or non-ideal backhaul links). An eCC may also be configured for use in unlicensed spectrum or shared spectrum (e.g., where more than one operator is allowed to use the spectrum). An eCC characterized by a wide carrier bandwidth may include one or more segments that may be used by UEs 115 that may not be able to monitor the entire carrier bandwidth or otherwise be configured to use a limited carrier bandwidth (e.g., to save power).

In some cases, an eCC may utilize a different symbol duration than other component carriers, which may include using a reduced symbol duration compared to the symbol duration of the other component carriers. Shorter symbol durations may be associated with increased spacing between adjacent subcarriers. A device utilizing an eCC (e.g., UE 115 or base station 105) may transmit a wideband signal (e.g., according to a frequency channel or carrier bandwidth of 20, 40, 60, 80MHz, etc.) with a reduced symbol duration (e.g., 16.67 microseconds). A TTI in an eCC may include one or more symbol periods. In some cases, the TTI duration (i.e., the number of symbol periods in a TTI) may be variable.

In addition, the wireless communication system 100 may be an NR system that may utilize any combination of licensed, shared, and unlicensed frequency spectrum bands. Flexibility in eCC symbol duration and subcarrier spacing may allow eCC to be used across multiple frequency spectrums. In some examples, NR sharing spectrum may improve spectrum utilization and spectral efficiency, particularly through dynamic vertical (e.g., across the frequency domain) and horizontal (e.g., across the time domain) sharing of resources.

In some wireless communication systems, data transmissions (e.g., target traffic) may be periodically broadcast from a UE 115 or base station 105. For example, in a V2X communication, a vehicle (e.g., or UE 115) may periodically broadcast a safety message (of known size) to enable nearby vehicles, sensors, or additional UEs 115 to receive the necessary information about the sending vehicle.

The wireless communication system 100 may support efficient techniques for establishing a unicast link (e.g., connection) between two wireless devices (e.g., UEs 115, vehicles, sensors, etc.). For example, a connection-oriented link may be established through the V2X layer of a protocol stack between two wireless devices that supports optimized AS layer configurations (e.g., over the air) to achieve higher throughput (e.g., 64 Quadrature Amplitude Modulation (QAM), CA, etc.), support enhanced security protection, and allow for more efficient resource usage (e.g., power control, beam management, etc.). In some cases, a unicast connection may be established on the sidelink 135 between two wireless devices, for example, without going through a base station. To establish a unicast connection on the sidelink 135, the first UE 115 may send a request message to the second UE 115, and the second UE 115 may send a response message to the first UE 115 accepting the request.

Additionally, the first UE 115 may send a connection complete message to the second UE 115 and establish a security context with the second UE 115 as part of establishing a connection over the sidelink 135. In some cases, the request message, response message, and connection complete message may be sent via RRC signaling (e.g., on PC5 with unified PC5 and Uu management). Additionally, the connection may be established based on parameters (e.g., capabilities, connection parameters, etc.) for the first UE 115 and/or the second UE 115 sent in the respective request messages and/or response messages. For example, the parameters may include PDCP parameters, RLC parameters, MAC parameters, PHY layer parameters, capabilities of any UE 115, or a combination thereof. Such communication may be performed as part of a link management process.

Turning next to fig. 2, fig. 2 is a block diagram illustrating some features of an apparatus for use in a UE configured for sidelink unicast communication based, at least in part, on one or more sidelink schedules negotiated with a peer UE, according to certain aspects of the present disclosure.

Referring to fig. 2, one example of an implementation of UE 115 may include various components, including components such as one or more processing units 212, memory 216, and transceiver 202 that communicate via one or more buses 244, which may operate in conjunction with modem 220 and communications component 222 to implement one or more functions described herein in relation to V2X and related communications. Further, the one or more processing units 212, modem 220, memory 216, transceiver 202, RF front end 288, and one or more antennas 265 may be configured to support (simultaneously or non-simultaneously) voice and/or data calls in one or more radio access technologies.

In an aspect, the one or more processing units 212 may include a modem 220 that uses one or more modem processors. Various functions associated with communications component 222 may be included in, or otherwise implemented at least in part in, modem 220 and/or processing unit 212, and in one aspect, may be performed by a single processor, while in other aspects, different ones of the functions may be performed by a combination of two or more different processors. For example, in an aspect, the one or more processing units 212 may include any one or any combination of the following: a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with the transceiver 202. In other aspects, some of the features of the one or more processing units 212 and/or the modem 220 associated with the communication component 222 may be performed by the transceiver 202.

Further, memory 216 may be configured to store data used herein and/or local versions of applications 275 for execution by at least one processing unit 212 of communication component 222 and/or one or more of the subcomponents of communication component 222. The memory 216 may include any type of computer-readable medium usable by the computer or at least one processing unit 212, such as Random Access Memory (RAM), Read Only Memory (ROM), magnetic tape, magnetic disk, optical disk, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory 216 may be a non-transitory computer-readable storage medium that stores one or more computer-executable codes defining all or a portion of communications component 222 and/or one or more of its subcomponents and/or data associated therewith when UE 115 operates at least one operating at least one processing unit 212 to execute communications component 222 and/or one or more of its subcomponents.

The transceiver 202 may include at least one receiver 206 and at least one transmitter 202. The receiver 206 may include hardware, firmware, and/or software code executable by a processor, the code comprising instructions and being stored in a memory (e.g., a computer-readable medium) for receiving data. Receiver 206 may be, for example, a Radio Frequency (RF) receiver. In an aspect, the receiver 206 may receive signals transmitted by at least one base station 105. The transmitter 208 may include hardware, firmware, and/or software code executable by a processor for transmitting data, the code comprising instructions and being stored in a memory (e.g., a computer-readable medium). Suitable examples of transmitter 208 may include, but are not limited to, an RF transmitter.

Further, in an aspect, the UE 115 may include an RF front end 288 that is operable in communication with the one or more antennas 265 and the transceiver 202 to receive and transmit radio transmissions, e.g., wireless communications transmitted by at least one base station 105 or wireless transmissions transmitted by the UE 115. The RF front end 288 may be coupled with one or more antennas 265 and may include one or more Low Noise Amplifiers (LNAs) 290 for transmitting and receiving RF signals, one or more switches 292, one or more Power Amplifiers (PAs) 298, and one or more filters 296.

In an aspect, LNA 290 may amplify the received signal at a desired output level. In an aspect, each LNA 290 may have a specified minimum gain value and maximum gain value. In an aspect, the RF front end 288 may use one or more switches 292 to select a particular LNA 290 and a specified gain value based on a desired gain value for a particular application.

Further, for example, one or more PAs 298 may be used by the RF front end 288 to amplify signals to achieve an RF output at a desired output power level. In an aspect, each PA 298 may have a specified minimum gain value and maximum gain value. In an aspect, the RF front end 288 may use one or more switches 292 to select a particular PA 298 and a specified gain value based on a desired gain value for a particular application.

Further, for example, one or more filters 296 may be used by the RF front end 288 to filter the received signal to obtain an input RF signal. Similarly, in an aspect, for example, a respective filter 296 may be used to filter the output from a respective PA 298 to produce an output signal for transmission. In an aspect, each filter 296 may be coupled with a particular LNA 290 and/or PA 298. In an aspect, the RF front end 288 may use one or more switches 292 to select a transmit path or a receive path using a specified filter 296, LNA 290, and/or PA 298 based on the configuration as specified by the transceiver 202 and/or the processing unit 212.

As such, the transceiver 202 may be configured to transmit and receive wireless signals through the one or more antennas 265 via the RF front end 288. In an aspect, the transceiver may be tuned to operate at a specified frequency such that the UE 115 may communicate with, for example, one or more base stations 105 or one or more cells associated with one or more base stations 105. In an aspect, for example, modem 220 may configure transceiver 202 to operate at a specified frequency and power level based on a UE configuration of UE 115 and a communication protocol used by modem 220.

In an aspect, the modem 220 can be a multi-band, multi-mode modem that can process digital data and communicate with the transceiver 202 such that the transceiver 202 is used to transmit and receive digital data. In an aspect, modem 220 may be multi-band and may be configured to support multiple frequency bands for a particular communication protocol. In an aspect, the modem 220 may be multi-mode and configured to support multiple operating networks and communication protocols. In an aspect, the modem 220 may control one or more components of the UE 115 (e.g., the RF front end 288, the transceiver 202) to enable transmission of signals and/or reception of signals from the network based on a specified modem configuration. In an aspect, the modem configuration may be based on the mode of the modem and the frequency band in use. In another aspect, the modem configuration may be based on UE configuration information associated with the UE 115 (as provided by the network during cell selection and/or cell reselection).

As shown in fig. 2, example communication component 222 may include a sidelink scheduler 240, which sidelink scheduler 240 may be configured to perform all or a portion of the techniques described herein, e.g., based at least in part on link availability schedule 224, sidelink negotiation information 226, or some combination thereof. The sidelink scheduler 240 may generate or otherwise provide one or more sidelink schedules 250, and the one or more sidelink schedules 250 may include or otherwise be based on a granularity 252, a timing offset 254, or some combination thereof that may be useful in providing sufficient information to the UE 115 for communicating over the sidelink. In some instances, a sidelink schedule selection indication 228 may be provided to determine which of the sidelink schedules 250 to use for sidelink communications. For example, the sidelink scheduling selection indication 228 may be set by the first UE and shared with the second UE, or vice versa. In some example implementations, the communication resource allocation 230 may be used to determine a link availability schedule and may be received from a network or other similar external resource. Further, as shown, a protocol stack 232 may be provided, the protocol stack 232 including one or more layers that may be used by the techniques herein.

With this in mind, attention is next drawn to fig. 3, which is a timeline 300 illustrating some example signaling procedures between two UEs (labeled UE1 and UE2) that may be used to establish a sidelink unicast communication therebetween, in accordance with certain aspects of the present disclosure. The example process 302 is represented by a first message exchange including an RRC connection setup with a direct link setup and a second message exchange including an RRC radio bearer configuration (for various QoS). Another example process 304 is represented by a message exchange that includes a MAC CE. Finally, the example process 306 is represented by L1 control and data transmission and corresponding HARQ feedback transmission. In timeline 300, a PC5 interface is shown as an example that may be used to support the techniques presented herein.

Fig. 4 illustrates portions of an example resource map 400, which example resource map 400 may indicate, at least in part, information for communication resource allocations 320, link availability schedules 224, and/or the like, in accordance with certain aspects of the present disclosure. By way of example, an LTE/NR, TDD configuration may include a map that indicates to a UE which time slot to use for UL and which time slot to use for DL, e.g., a partial resource map 400 listing different subframes allocated for uplink communication (labeled "U"), downlink communication (labeled "D"), or unused (labeled "U").

Fig. 5 illustrates some example link availability schedules 500 for a UE in accordance with certain aspects of the present disclosure. For example, for Config-index1, the example link availability schedule 502 shows a sequence of blocks representing all or a portion of one or more time slots (e.g., depending on granularity) corresponding to a communication resource (e.g., corresponding to time and frequency characteristics). In this example, all blocks may be used for transmission or reception. Here, for example, "T" indicates a transmission capability and "R" indicates a reception capability. Similarly, in Config-index 2, the example link availability schedule 504 illustrates a sequence of blocks representing all or a portion of one or more time slots (e.g., depending on granularity) corresponding to a communication resource (e.g., corresponding to time and frequency characteristics). Here, for example, in addition to the "T" and "R" blocks, "U" blocks indicating unavailable or unused (at least for sidelink communications) are included.

In some example implementations, as part of the sidelink scheduler 240 (see fig. 2), an RRC procedure or other similar sidelink establishment procedure may be configured to support a unidirectional flow case, e.g., where the Transmitting (TX) UE needs to be aware of the link availability schedule of the Receiving (RX) UE. For a particular QoS for sidelink unicast streams, the AS layer parameters may be configured for DRBs (data radio bearers) before data transmission can occur. Here, for example, a part of the MAC-config may be used to decide/configure "link availability" that limits any resource usage of the DRB by the TX UE. Note, however, that in some instances, "link availability" does not necessarily mean that the resources in the schedule are "dedicated" to the TX UE for transmission. Instead, this may help the TX UE to avoid selecting resources that the peer UE does not want to use for reception. For example, the TX UE may make resource selections within the boundaries of RX scheduling of the peer UE, etc.

For uni-directional unicast flows (TX UE has traffic for RX UE, not in other directions), UE1 (see fig. 3) may include one or more QoS parameters (e.g., data rate/periodicity, delay budget, etc.) and proposed AS layer configuration in RRC message 1 (e.g., may include RRCConnectionSetupRequest, rrcconnectionreconfiguration, etc.). UE2 (see again fig. 3) may determine the higher layer "link availability" for the flow and include it in a response message (e.g., RRC message 2). In some instances, the link availability schedule may include a so-called "white list" based on the resources available for reception. Conversely, in some instances, the link availability schedule may include a so-called "blacklist" based on resources that are not available for reception. In another example, a bitmap or other similar set of data may be used to indicate both resources available for reception and resources not available for reception. In some example implementations, message 2 may also be used to indicate a negotiation failure, for example, if UE2 is very busy/congested and the QoS requirements from UE1 are considered too high to be supported.

In some example implementations, as part of the sidelink scheduler 240 (see fig. 2), an RRC procedure or other similar sidelink establishment procedure may be configured to support bi-directional streaming sidelink unicast communications. Here, for example, it is assumed that an RRC procedure or other similar procedure is to negotiate parameters for a bidirectional flow (reciprocal service). Thus, in this case, each peer UE acts as a TX UE and also as an RX UE. Thus, the link availability schedule may include a TX/RX schedule. Depending on the estimated traffic volume or some other aspect, peer UEs may agree on different TX/RX splits (e.g., 50/50, 60/40 or 40/60,.. 80/20 or 20/80, etc.). The RRC procedure or other similar procedure may be configured to allow a wider negotiation procedure to occur, for example, because two UEs may need to check their own link availability schedules and the link availability schedules of peer UEs to agree on one or more sidelink schedules and/or candidate or alternative sidelink schedules. In some instances, such procedures may include 3-way or 4-way "handshake" based procedures, and the like. Note that the TX/RX scheduling that may be exchanged in some implementations may be considered somewhat "raw" and still obey the final resource selection protocol, since some sidelink communication may use a common channel shared with other UEs in the vicinity, such that each time slot/subframe may still be left to contend. In some instances, bidirectional flow sidelink scheduling negotiation may also be supported by establishing at least two unidirectional flows, each of which may be negotiated separately, e.g., as previously described.

The example Tx/Rx scheduling negotiation may include a two-step process in which a combined Tx/Rx sidelink schedule may be established based at least in part on a link availability schedule of the UE. Here, for example, in a first step, each UE may share sidelink negotiation information corresponding to its individual TX/RX availability and/or TX/RX unavailability, e.g., based at least in part on a respective link availability schedule, etc. In some example implementations, such information may include a bitmap or other similar data format that is easily compared. Two applicable bitmaps (e.g., one bitmap from each UE) may be processed (e.g., applying a logical AND operation, etc.) to quickly identify commonalities with respect to blocks (e.g., each block includes one or more time slots). In a second step, the UE may determine which of these available blocks or portions thereof may include TX and RX slots, etc. Such a determination may, for example, take into account QoS or other similar aspects associated with sidelink unicast communications. An attempted sidelink connection may be deemed to have failed if the resulting TX/RX (and possibly unavailable) candidate sidelink schedule may not meet the QoS of the DRB. However, in some instances, it may be determined that the QoS or other relevant factors may be changed in some manner (e.g., reduced, degraded, etc.) to allow the attempted sidelink connection to continue accordingly. Indeed, as described in more detail below, in certain cases it may be useful for the UE to adapt/reconfigure the sidelink unicast connection in a dynamic manner (e.g., to account for changing conditions, etc.).

Another example Tx/Rx scheduling negotiation may include a one-step process in which a combined Tx/Rx sidelink schedule may be established based at least in part on a link availability schedule for the UE. Here, for example, the UE1 may propose one or more TX/RX sidelink schedules to the UE 2. The candidate sidelink scheduling may, for example, be based at least in part on knowledge of traffic requirements (in both directions) and applicable constraints (e.g., QoS, data, timing, etc.) for the UE 1. In response, if two or more candidate sidelink schedules have been demonstrated, the UE2 may select one candidate sidelink schedule that is deemed acceptable. In some instances, the UE1 may indicate a priority or preference with respect to each of the candidate sidelink schedules, e.g., to inform the UE2 of a preferred selection order. The UE2 may send an indication of the selected candidate sidelink scheduling to the UE 1. Further, as mentioned, in some implementations, the UE1 and UE2 may be configured to allow for dynamic changes, such as changing from one candidate sidelink scheduling to another candidate sidelink scheduling at different times, e.g., by sending an applicable indication, etc. If the UE2 cannot agree on the candidate scheduling given by the UE1, the UE2 may reject the message (and optionally include one or more alternative candidate sidelink schedules for consideration by the UE 1). In some example implementations.

As suggested, in certain implementations, it may be useful for the UE to dynamically alter or otherwise adjust the sidelink scheduling being used. The change may be useful, for example, if one of the UEs is already engaged in new traffic and therefore needs to change the RX part of the sidelink scheduling. In another example, with respect to the TX portion of the sidelink schedule, the change may be useful for UEs with some bursty traffic for the stream.

In some example implementations, one or more sidelink schedules may be renegotiated by restarting the negotiation/connection process, e.g., as previously described. Thus, through RRC reconfiguration, a new sidelink schedule can be negotiated for the DRB. However, some delay may be expected.

In another example, the sidelink scheduling may be changed rapidly based on an indication from one UE to another UE to switch to a different sidelink scheduling in a previously considered set of candidate sidelink schedules. Here, such example sidelink scheduling changes may be performed, for example, via a MAC CE (e.g., L2 signaling, etc.), where the candidate sidelink scheduling sets are pre-negotiated, for example, during RRC. The MAC CE may, for example, respond to an indication (e.g., index, identifier, etc.) of the new sidelink schedule to trigger a handover with the new schedule so that the UE may adjust its resource selection limit accordingly.

Sidelink scheduling may include various formats depending on the situation, design aspects, etc. In some non-limiting example implementations, the sidelink schedule may indicate a scheduling granularity, e.g., for a block or time slot being considered. For example, the scheduling granularity may indicate 1, 5, 10, 20, 50, …, M subframes, e.g., depending on latency requirements. If an "N subframe" time period is blocked by an RX UE without qualification for "RX," traffic arriving during such time period may suffer a delay of up to N subframes. The sidelink schedule may also indicate its purpose or type, e.g., Rx-only schedule (link availability) or TX/Rx schedule. The sidelink schedule may also indicate a corresponding start frame (e.g., timing offset) and period, e.g., for bitmap configuration. In some instances, the common configuration may be pre-configured in RRC signaling or configured by the network, possibly allowing an index to be used, etc.

Attention is next drawn to fig. 6, which illustrates aspects of an example sidelink scheduling procedure 600, in accordance with certain aspects of the present disclosure. Here, the example "original" schedule 602 shows available resources labeled "a" (which may be used for transmission or reception) for a UE, as well as other unavailable resources labeled "U". The original schedule may include or be based at least in part on a link availability schedule and/or a communication resource allocation. The corresponding proposed sidelink schedule 604 that may be provided or otherwise indicated to the peer UE in the sidelink negotiation information shows: some resources marked "a" in the original schedule 602 may be targeted for possible transmission (marked "T") or possible reception (marked "R") accordingly. Additional corresponding example candidate sidelink schedules 606 may be negotiated, wherein resources may be reduced to match desired granularity, parameters, and the like. As shown by the reduced width of the candidate sidelink schedule 606 (compared to the proposed sidelink schedule 604), the granularity has been reduced (at least with respect to time) for the resources to be used. Similarly, as the sidelink schedule becomes consistent during negotiation, the granularity with respect to frequency may also change.

Fig. 7 illustrates an example scenario 700 in which a UE1 may need to engage in sidelink communications with multiple UEs. Here, it may be desirable to determine a "link availability" schedule involving multiple links. In this example, considering link availability schedule 702, UE1 may currently be transmitting to UE2 using some resources, while other available resources are unused. UE3 and UE4 may each intend to establish a unidirectional flow to UE1, and thus, for example, UE1 may use or otherwise indicate link availability schedule 704. Thus, UE3 and UE4 may each attempt to negotiate the use of "a" (available) blocks of pairs instead of the "U" blocks corresponding to the TX blocks of schedule 702. It should be appreciated that the UE1 may receive during three "a" blocks in both schedules 702 and 704.

Fig. 8 illustrates an example scenario 800 where UE1 may need to engage in sidelink communications with multiple UEs. Here, it may be necessary to determine a "TX/RX/U" schedule involving multiple links. In this example, the UE1 may be currently transmitting/receiving with the UE2 using some resources, for example, in view of the link availability schedule 802, while other resources are unused. If the UE1 intends to establish a bi-directional flow to the UE3, the UE1 may consider using a link availability schedule 804 in negotiation with the UE3, the link availability schedule 804 making the two links (UE1-UE2 and UE1-UE3) orthogonal in the time domain. Here, UE3 may propose to be in RX mode in block 2, while UE2 is in RX mode in block 3 and slot 4. Alternatively, referring to the example link availability schedule 806, the UE1 may propose to reuse a portion or all of the T/R slots for both the UE1-UE2 and UE1-UE3 links, and reserve unused slots for future use.

Turning next to fig. 9, fig. 9 is a flow diagram illustrating an example method 900 for use in a UE configured for sidelink unicast communication based, at least in part, on one or more sidelink schedules, e.g., as illustrated in fig. 2, in accordance with certain aspects of the present disclosure.

At example block 902, a first UE may obtain a link availability schedule that indicates, at least in part, communication resources available for use by at least the first UE for sidelink unicast communications. By way of some examples, all or a portion of the link availability schedule may be based at least in part on local processing, configuration, or other like usage considerations of the first UE, communication resource allocations associated with one or more networks, and the like, or some combination thereof.

At example block 904, the first UE may identify a second UE attempting to participate in the sidelink unicast communication. Here, for example, the first UE may identify the second UE based at least in part on signals received from the second UE and/or signals received from one or more other devices, preconfigured information stored in a memory of the UE, sensor-based information, user input, and/or the like.

At example block 906, the first UE may establish a sidelink schedule with the second UE. Here, for example, the sidelink schedule may correspond to at least a subset of the communication resources indicated by the link availability schedule. At optional block 908, the first UE may exchange sidelink negotiation information with the second UE. At optional block 910, the first UE may receive sidelink negotiation information from the second UE. At optional block 912, the first UE may identify one of two or more candidate sidelink schedules to use as the sidelink schedule. At optional block 914, the first UE may receive an indication from the second UE that one of the two or more candidate sidelink schedules is to be used as a sidelink schedule.

At example block 916, the first UE may establish a sidelink with the second UE, and at example block 918, the first UE may communicate (transmit and/or receive) with the second UE via the sidelink using at least a portion of the communication resources according to a sidelink schedule.

It should be noted that the methods described herein describe possible implementations, and that the operations and steps may be rearranged or otherwise modified, and that other implementations are possible. Further, aspects from two or more methods may be combined.

The electromagnetic spectrum is often subdivided by different authors/entities into differently identified classes, bands, channels, etc. based on frequency/wavelength. For example, a portion of the electromagnetic spectrum from 30Hz to 300GHz is commonly referred to as the radio spectrum, where the corresponding electromagnetic waves are commonly referred to as radio waves.

For example, the International Telecommunications Union (ITU) currently identifies twelve different named frequency bands in the radio spectrum based on power at a wavelength of 10 meters. Here, for example, modern wireless communications are of particular interest for ITU at certain radio frequencies/bands within the Very High Frequency (VHF) band (30MHZ-300MHZ), the Ultra High Frequency (UHF) band (300MHZ-3000MHZ), the ultra high frequency (SHF) band (3000MHZ-30000MHZ), and/or the Extremely High Frequency (EHF) band (30000 MHZ-300000 MHZ).

In another example, the Institute of Electrical and Electronics Engineers (IEEE) acknowledges the same VHF and UHF bands of the ITU, but divides the radio spectrum (300 MHz-300000 MHz) corresponding to the UHF, SHF, and EHF bands of the ITU into ten different named bands.

One of the problems that may arise from naming parts of the radio spectrum by different authors/entities is that some potential confusion may arise. For example, the ITU's EHF band (30000 MHz-300000 MHz) corresponds to wavelengths between 1mm and 10mm, and is therefore commonly referred to as the millimeter wave band. However, the (narrower) IEEE band designated as the "G" band (110000 MHz-3000000 MHz) is also commonly referred to as the millimeter wave band.

For the 5G New Radio (NR), the two initial operating frequency bands have been identified by the frequency range names FR1(410MHz-7125 MHz) and FR2(24250 MHz-52600 MHz). It is contemplated that other frequency range names may be identified for 5G or later generations. Even if a portion of FR1 is greater than both 6GHz (>6000MHz) and 7GHz (>7000MHz), FR1 is commonly referred to in various documents and articles on the subject of 5G NR as being below the 6GHz band or below the 7GHz band. Similar naming problems with FR2 sometimes occur in various documents and articles on the subject of 5 GNR. Although a portion of FR2 is less than 30GHz (<30000MHz, e.g., the low end of the EHF band), FR2 is commonly referred to as the millimeter wave band in various documents and articles on the subject of 5G NR. Furthermore, all or some of the frequencies between the upper limit of FR1 (currently 7125MHz) and the lower limit of FR2 (currently 24250MHz) are commonly referred to as mid-band frequencies.

In view of the above, unless otherwise specifically stated, it should be understood that if the term "below 6 GHz" or the like is used herein by way of example, it may represent all or a portion of FR1 for 5G NR. Further, unless specifically stated otherwise, it should be understood that if the term "millimeter wave" is used herein by way of example, it may mean all or a portion of FR2 for 5G NR and/or all or a portion of EHF band.

It should also be understood that the terms "below 6 GHz" and "millimeter wave" are also intended herein to mean modifications to such example frequency bands that may result from author/entity decisions regarding wireless communications, e.g., as given by example herein. For example, unless specifically stated otherwise, it should be understood that if the terms "below 6 GHz" or "millimeter wave" are used herein, it may also refer to corresponding (non-overlapping) portions of so-called mid-band frequencies.

It should be understood that the above examples are not necessarily intended to limit the claimed subject matter. For example, unless specifically recited, the claimed subject matter related to wireless communications is not necessarily intended to be limited to any particular author/entity defined frequency band or the like.

The techniques described herein may be used for various wireless communication systems such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and others. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), and so on. CDMA2000 covers IS-2000, IS-95 and IS-856 standards. The IS-2000 version may be generally referred to as CDMA 20001X, 1X, etc. IS-856(TIA-856) IS commonly referred to as CDMA 20001 xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes wideband CDMA (W-CDMA) and other variants of CDMA. TDMA systems may implement radio technologies such as global system for mobile communications (GSM).

An OFDMA system may implement radio technologies such as: ultra Mobile Broadband (UMB), evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE)802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, flash-OFDM, and the like. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE, LTE-A and LTE-A specialties are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE-A, LTE-A specialty, NR, and GSM are described in documents from an organization named "3 rd Generation partnership project" (3 GPP). CDMA2000 and UMB are described in documents from an organization named "3 rd generation partnership project 2" (3GPP 2). The techniques described herein may be used for the systems and radio techniques mentioned herein as well as other systems and radio techniques. Although aspects of the LTE, LTE-A, LTE-a specialty, or NR system may be described for purposes of example, and LTE, LTE-A, LTE-a specialty, or NR terminology may be used in much of the description, the techniques described herein may be applicable to ranges outside of LTE, LTE-A, LTE-a specialty, or NR applications.

A macro cell typically covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell may be associated with a lower power base station than a macro cell, and the small cell may operate in the same or different (e.g., licensed, unlicensed, etc.) frequency band as the macro cell. According to various examples, the small cells may include pico cells, femto cells, and micro cells. For example, a pico cell may cover a small geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a residence) and may provide restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in the residence, etc.). The eNB for the macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, pico eNB, femto eNB, or home eNB. An eNB may support one or more (e.g., two, three, four, etc.) cells and may also support communication using one or more component carriers.

The wireless communication systems described herein may support synchronous or asynchronous operation. For synchronous operation, UEs may have similar frame timing, and transmissions from different UEs may be approximately aligned in time. For asynchronous operation, UEs may have different frame timing, and transmissions from different UEs may not be aligned in time. The techniques described herein may be used for synchronous or asynchronous operations.

The information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the specification may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general purpose processor, a DSP, an ASIC, an FPGA or other PLD designed to perform the functions described herein (e.g., with respect to one or more processing units), discrete gate or transistor logic, discrete hardware components, or any combination thereof. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hard wiring, or a combination of any of these. Features implementing functions may also be physically located at various locations, including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. Non-transitory storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media can comprise RAM, ROM, electrically erasable programmable ROM (eeprom), flash memory, Compact Disc (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Further, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes CD, laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

As used herein (including in the claims), a "or" as used in a list of items ending with a phrase such as "at least one of" or "one or more of" indicates an inclusive list such that, for example, a list of at least one of A, B or C means a or B or C or AB or AC or BC or ABC (i.e., a and B and C). Further, as used herein, the phrase "based on" should not be construed as a reference to a closed set of conditions. For example, exemplary steps described as "based on condition a" may be based on both condition a and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on" is interpreted.

In the drawings, similar components or features may have the same reference numerals. In addition, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description applies to any one of the similar components having the same first reference label irrespective of the second or other subsequent reference label.

The description set forth herein in connection with the appended drawings describes example configurations and is not intended to represent all examples that may be implemented or within the scope of the claims. The term "exemplary" as used herein means "serving as an example, instance, or illustration," rather than "preferred" or "advantageous over other examples. The detailed description includes specific details for the purpose of providing an understanding of the described technology. However, the techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

The description herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.